1. Field of the Invention
The invention relates generally to protective cases for storing and shipping disc-shaped information storage media such as compact discs and digital video disks and, more particularly to protective jewel cases of a clam-shell design comprising an assembly of three pieces: a bottom cover piece, a top cover piece hingeably connected to the bottom cover piece, and an internal swing-out piece hingeably connected to the bottom cover piece.
2. History of the Prior Art
The use of optically-scannable discs for high-density storage of digital data has exploded since the advent of the compact disc (CD) in 1983. Capable of storing 650 to 700 megabytes of digital data, a single CD could hold 74 to 80 minutes of high-quality music. Fourteen years later, the digital video disc (DVD) was introduced. Although a DVD is identical in thickness (1.2 millimeters) and diameter (120 millimeters or 4.7 inches) to a standard CD, the DVD's storage capacity is seven times that of a CD, with a 4.7-gigabyte capacity on a single-side, single-layer DVD. Ninety-five percent of all movies are 133 minutes or less in length, and fit comfortably on a such a DVD. A single-side, dual layer DVD has nearly double the capacity (8.5 GB), and a double-sided, dual-layer DVD has nearly four times the capacity (17 GB). The DVD is an ideal storage medium for not only movies, but for high-definition computer games and multimedia applications, as well.
Pressed CDs and DVDs are manufactured using very similar processes. In order to produce a pressed CD or DVD, polycarbonate plastic is injected into a mold containing a negative master disc. As the disk must reflect laser light, a gold, silver, copper or aluminum layer of about 50 to 100 nanometers in thickness is then applied to the pressed surface via sputtering or vacuum deposition. Because it is the least expensive, aluminum is used for virtually all prerecorded pressed discs. When greater reflectivity is required for recordable disks, gold or silver is used. A thin layer of acrylic plastic is then applied on top of the metal layer by spin coating. After it is cured in ultraviolet light, the acrylic plastic protects the metal layer from scratches and corrosion. Extra protective or printer-friendly coatings may also be subsequently spun on. Because the degree of mechanical damage protection provided by the acrylic plastic layer is fairly minimal, CDs and DVDs are relatively fragile and must be handled with care in order to ensure their longevity.
The ideal case should have a manufacturing cost that is considerably less than that of the CD or DVD which it protects. It should also be sufficiently durable so that, if given reasonable care, will last as long as the CD or DVD. Reasonable care must include frequent openings and closings, occasional dropping, as well as rough handling during shipping and processing on an automated assembly line. The ideal case must also be capable of retaining and displaying labels which identify or advertise the CD or DVD contained therein. Manufacturers, merchants and consumers have demonstrated a preference for cases which are compact and easily stored. The size for 3-piece polystyrene jewel cases has become standardized at 142 mm×125 mm×10 mm.
The ubiquitous clam-shell-type jewel case that was developed to protect CDs during display, shipment and storage is a design compromise. Each case is injection molded from polystyrene as three separate components: a top half, or lid; a bottom half, which hingeably interconnects with the lid; and an inner tray, which snaps into the bottom half and holds the CD. Though the polystyrene used to fabricate the cases is quite brittle, its crystal clarity makes it an idea material for the display of labels secured within the case. Though cases made from impact resistant polyethylene and polypropylene have been manufactured, they lack the clarity of the polystyrene cases. Consequently, they are rarely used as original retail cases. Though half-thickness CD cases are also now available, the display of labels is limited to the upper half, as the lower half and media tray are unitary.
Though standard polystyrene jewel cases continue to be used for the packaging of pressed CDs, a different format has become standard for DVDs. While maintaining the same width and thickness as the standard CD jewel case at 142 mm and 10 mm, respectively, the height has increased to 191 mm. Presumably, the increase in height was ordained to accommodate a larger internal booklet. Typically, the DVD cases are injection molded from polyethylene or polypropylene material. Although the durability of the cases is enhanced, the cost is increased because clear plastic sheet material must be heat bonded to the outer surface of the case to form slip pockets. In addition, printed paper labels must be inserted into the pockets. Thus, appearance and low cost have taken a back seat to durability.
One of the problems associated with the standard jewel CD case is the vulnerability of the cover hinge arms to mechanical damage. Given the inherent weakness of the standard case, it is absolutely amazing that the design has remained unchanged for more than twenty years.
U.S. Pat. No. 5,890,590 to Peter J. Doodson discloses jewel cases featuring improved hinge design for standard-size CD and DVD cases. Each of the cases has a pair of recessed hinge arms and a pair of corresponding recessed hinge walls. Each hinge arm has an inner wall with a first pivot component and a parallel outer protective wall. Each recessed hinge wall has a second pivot component that mates with a first pivot component on an associated hinge arm.